Hello!
The safest and best way to deal with cyberbullying is to report any threats of harm to the police.
Cyberbullying is a form of harassment or bullying using electronics. Typically, the bully sends messages that can intimidate you, or it has a threatening nature to it. It includes posting, sharing, or revealing negative, hurtful and sometimes false information about the victim. Reporting any threats to the police can help you feel safer, and can pose a threat to the bully.
So therefore, the answer is D, report any threats of harm to the police.